Bluetooth ear pieces I need to be able to use two ear pieces with a phone

What I'm trying to do, is find some Bluetooth ear pieces that will work
as a pair to the same mobile, so two people can communicate (using said
ear pieces) with someone on the phone.

The 'dated' hands-free kit (Nokia CARK99 - I think, with Nokia 6210
phone) presently in my vehicle (very noisy) is okay, but callers tend
to get freaked out by the background noise, so thought updating the
phone to use Bluetooth technology would be the way to go. But it seems
I need to sort the ear pieces out first

The eventual aim is to have a mobile that
1. Can be used as a modem with my laptop (either by
cable/Ir/Bluetooth).
2. Perhaps have a camera, though not top priority
3. Have Bluetooth capability.
4. Used with a pair of Bluetooth ear pieces.
5. Capable of using a twin sim adaptor (to receive from two numbers
without having to manually switch numbers, otherwise I'm back to two
phones)

With regards to phones, I had been looking at a Sony Ericsson K550i,
but this doesn't work with 4 and 5 above.

My budget is limited, so not willing to spend hundreds.

Can anyone help with the above please, or even suggest some
alternatives?

Thanks in advance for any help etc.




--
eor